powdery-mildewPowdery mildew

Apple powdery mildew (Podosphaera leucotricha f.c oidium farinosum) – identify and control

Apple powdery mildew-identify-and-control

Apple powdery mildew, Podosphaera leucotricha fc oidium farinosum is present on all continents and affects apple trees orchards.

Symptoms. The disease manifests itself throughout the growing season, from bud burst until leaf fall, with higher intensity during May and early June. Leaves, flowers, shoots, and sometimes young fruits are attacked. The attack on the young leaves appears in the form of a whitish, powdery growth that covers both sides of the leaf. In a short time, the leaves curl up slightly, are less elastic, and dry out prematurely.

The fungus quickly attacks the young shoots, which it covers with whitish, powdery growth, due to the formation of spores, and towards autumn it turns brown after the formation of the pathogen fructifications. Strongly attacked shoots bend in the shape of a hook and dry. The attacked flowers have deformed petals, sometimes even split in two, lose their white-pink color and become white, and in some cases thicken, wither, and turn brown.

The attacked flowers, dry out without forming fruit. In apple varieties susceptible to powdery mildew, this form of attack leads in some years to significant crop losses. The attack on the young fruits causes a stop of the growth and in some cases, even a fall of them.

The pathogen is Podosphaera leucotricha fc oidium farinosum. The fungus overwinters as a mycelium in vegetative or flower buds, which were infected in the previous season. In spring, after the end of the dormancy period, the powdery mildew fungus resumes growth and colonizes developing shoots causing primary infections.

Prevention and control. To prevent the disease, it is recommended that the strongly attacked shoots be permanently pruned and destroyed by burning and also the cultivation of resistant apple varieties. During the growing season, treatments with specific fungicides will be applied.

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Apple powdery mildew (Podosphaera leucotricha f.c oidium farinosum) – identify and control
Apple powdery mildew (Podosphaera leucotricha f.c oidium farinosum) – identify and control

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